Flexible tubular device for use in medical applications

ABSTRACT

Manufacturing processes for apparatus, including slotted hypotube, for use as a catheter, a guidewire, a catheter sheath for use with catheter introducers or a drug infusion catheter/guidewire are disclosed. The manufacturing process includes creating a pattern of slots or apertures in a flexible metallic tubular member, by processes including but not limited to, electrostatic discharge machining (EDM), chemical milling, ablation and laser cutting. These slots or apertures may be cut completely or partially through the wall of the flexible metallic tubular member. These manufacturing processes may include the additional step of encasing the flexible metallic member such that a fluid tight seal is formed around the periphery of the tubular member.

The following is a continuation-in-part of application Ser. No.08/329,691, filed Oct. 26, 1994, now U.S. Pat. No. 5,573,520, which is acontinuation of 07/940,657, filed Sep. 4, 1992, now abandoned, which isa continuation-in-part of Ser. No. 07/755,614, filed Sep. 5, 1991, nowabandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a biocompatible flexible tubular devicefor insertion into the body during medical procedures. Moreparticularly, the invention relates to flexible tubular devices for useas catheters, including guide catheters and balloon catheters,guidewires, catheter sheaths, catheter introducers, drug infusioncatheters/guidewires, and methods for making the same.

Catheters and Guidewires

Catheters are relatively thin and flexible tubes used in the medicalfield for numerous applications. Catheters are made by any number ofdifferent methods and designs. However, in most catheter designs it isdesirable to obtain a maximum torsional rigidity while retaining asatisfactory longitudinal flexibility and stiffness without kinking.These features will allow the orientation of the catheter to bemanipulated so that the catheter can be guided through small bodyvessels and cavities. These features will also prevent any kinking fromoccurring, and provide the catheter with enough "push" or stiffness soas to prevent the catheter from wrinkling or folding back on itselfduring this process. The specific nature of these characteristics willof course vary depending on the specific application for which thecatheter is being used. Yet another consideration is that a relativelysmall outside diameter must be maintained while providing a lumen or aninside diameter as large as possible.

Guide wires require the same general type of characteristics. However,with guide wires it is important to minimize the outside diameter of theguide wire so that they will readily fit inside of the lumen of thecatheter.

Catheters and guide wires are used both as diagnostic tools and in thetreatment of diseases. One such diagnostic procedure is cardiaccatheterization which is a widely performed procedure, being used forassessment of coronary artery disease. Other uses are neurologic uses,radiologic uses, electrophysiologic uses, peripheral vascular uses, etc.One example of a treatment use is the use of balloon catheters indilation procedures to treat coronary disease. Dilation procedures relyupon the use of a catheter for injection of contrast and delivery ofguidewires and dilation catheters to the coronary artery or otherarteries. An example of the use of guide wires is for PercutaneousTransluminal Coronary Angioplasty (PTCA) balloons and for guidingdiagnostic catheters through the arteries and to body organs.

The catheters and guide wires used in these and other procedures musthave excellent torque characteristics, and must have the requisiteflexibility. In addition, it is important that catheters and guidewiresprovide sufficient longitudinal support for "pushing" of items throughthe arteries and other vessels such as when feeding the balloon portionof an angioplasty catheter through the arteries. Unless there issufficient stiffness, the catheter or guidewire will wrinkle or foldback on itself.

Typically, in the case of a catheter, the larger the ratio of inside tooutside diameter, the better. For guide wires it is important tomaintain a small outside diameter. Smaller catheter and guidewireoutside diameter sizes result in less chance of arterial damage.

Catheters and guide wires must have sufficient torque such that they donot buckle when being manipulated. Finally, flexibility is important sothat the catheter or guide wire can be manipulated into the varyingarterial branches encountered by the catheter. The guide wire mustresist being inadvertently kinked as this results in loss of torquecontrol.

Prior art catheters are typically made of flexible materials which arereinforced such that the resulting composite catheter approximates thedesired characteristics. In alternative approaches, guide wires are usedin conjunction with catheters to assist in manipulating and moving thecatheters through the arterial system in the body.

U.S. Pat. No. 4,020,829 to Willson et al. discloses a spring guide wirefor use in catheterization of blood vessels. The guide wire is axiallyslidable within a thin walled, flexible plastic catheter. The distalportion of the guide wire is of a relatively short length and isconnected to a relatively long, manipulative section capable oftransmitting rotational torque along its length. In this invention thecatheter tube might be advanced over the guide wire after the guide wirehas been properly positioned or the catheter might be advanced togetherwith the guide wire, the guide wire providing a reinforcement for thethin wall of the catheter.

U.S. Pat. No. 4,764,324 to Burnham discloses a method for making acatheter. In Burnham, a reinforcing member is heated and applied to athermoplastic catheter body so as to become embedded in the wall of thecatheter. The wall of the catheter is then smoothed and sized so as toproduce a composite, reinforced catheter.

The art of applying braiding or multi-pass wire reinforcement to acatheter inner core is also well developed and machinery for performingsuch a step is well known. Typically, such reinforcement material isapplied to the inner core tube of the catheter in a pattern ofoverlapping right and left hand helices. The braiding process usuallyrequires that the machinery performing the braiding process to move thereinforcement material alternately radially inwardly and outwardly, aswell as circularly, whereby the tension of the reinforcement materialcontinuously varies. This varying tension can result in thereinforcement material breaking particularly as the speed of braidingincreases. Yet another problem with braided catheters is that theirinside diameter is relatively small compared to their outside diameter.The braids are quite loose also.

Current catheters often suffer from either problems of torque, size,flexibility, kinking, and poor support during PTCA in the case of guidecatheters. Moreover, catheters cannot be readily made with variablestiffness along the length of the catheter.

Catheter Sheaths and Introducers

Catheter sheaths and introducers are used to provide a conduit forintroducing catheters, fluids or other medical devices into bloodvessels. A catheter introducer typically comprises a tubular cathetersheath, a hub attached to the proximal end of the sheath havinghemostasis valve means to control bleeding and to prevent air embolisms,and a removable hollow dilator that is inserted through the hub, valvemeans and the lumen of the catheter sheath. Many catheter introducersalso contain a feed tube that is connected to the hub to facilitate theintroduction of fluids into the blood vessel.

The procedure for positioning the introducer into a blood vessel beginsby inserting a hollow needle through the skin and into the lumen of thedesired blood vessel. A guidewire is then passed through the needle andinto the blood vessel. The needle is then removed leaving the guidewirein the vessel. Next, the sheath and dilator are advanced together overthe guidewire until the distal ends of the dilator and sheath arepositioned within the lumen of the vessel. The guidewire and dilator arethen removed, leaving the distal end of the sheath within the vessel.Catheters or other medical devices can then be passed through theintroducer and sheath into the desired vessel.

Conventional sheaths are made of plastic and as shown in FIG. 14, aresubject to kinking if bent without internal support. This kinking canoccur during the insertion of the device or if the patient moves whilethe sheath is in the vessel. Unfortunately, this kinking can createsharp edges or irregularities in the sheath that can damage blood vessellinings. This kinking can also make the introduction of devices orfluids more difficult and can cause patient bleeding problems around thesheath tubing. Therefore, there arises a need for a catheter introducerwith a catheter sheath that is flexible and resistant to kinking.

Conventional catheter sheaths also have a limited hoop strength makingthem susceptible to burring or notching. This burring and notching canoccur during the insertion of the sheath and dilator into the bloodvessel or if the forces exerted on the sheath cause it to becomenon-circular. These burrs and notches can also damage blood vessellinings. Therefore, there arises the need for a catheter sheath that hassufficient hoop strength to prevent deformation in the sheath to resistthe formation of burrs or notches.

It is also important that the sheath have a minimum thickness to reducethe size of the puncture hole in the blood vessel. Larger puncture holesmake hemostasis more difficult upon removal of the sheath. The sheathshould also be lubricous to make the insertion and extraction of thesheath and other devices easy. Therefore, there arises the need for acatheter sheath for use with a catheter introducer that has a thin wall,that is flexible and resistant to kinking, that is lubricous, and thathas sufficient hoop strength to prevent the catheter sheath from burringor notching.

One method for creating a sheath that may meet the above requirementswould be to make the sheath from expanded polytetrafluoroethylene (PTFE)as disclosed in U.S. Pat. No. 5,066,285. While PTFE is more flexible andhas a higher hoop strength than the plastics used in conventionalsheaths, it is still a plastic-type material that may be subject to thesame deformation problems.

Drug Infusion Catheters/Guidewires

Drug infusion catheters/guidewires are devices that act like bothcatheters and guidewires and are capable of delivering drugs or otherfluids to a specific location within a patient's blood vessel such as anoccluded blood vessel. The guidewire type devices are typicallycomprised of a coil spring with a heat shrunk TEFLON® coating and a corewire that can be inserted and removed from the lumen in the coil spring.The coated coil also contains either side holes or an end hole or acombination thereof in its distal end to enable the drugs or otherfluids to be sprayed into the blood vessel.

During use, the coated coil spring and its core wire are advancedtogether through the patient's circulatory system much like conventionalguidewires. Upon reaching the desired location, the core wire is removedcreating a small catheter like device. Drugs or other fluids are pumpedthrough the lumen in the coated coiled spring, out of the holes and intothe blood vessel at the desired location.

Because these devices act like guidewires, the outside diameter of thedevices, and therefore the lumen, are limited in size. Therefore, asecond type of drug infusion catheter/guidewire device utilizes acatheter like member with side holes and a tapered distal end having anend hole generally equal to the outside diameter of a guidewire. Thesecatheter type drug infusion catheter/guidewire devices are advanced overa guidewire to the desired location and then drugs are then pumpedthrough and out of the holes in the catheter like member. These devicescan also be used in combination with the guidewire type drug infusiondevices.

As described above, drug infusion catheter/guidewire devices act likeboth catheters and guidewires. Therefore, these devices must have thesame characteristics as catheters and guidewires. These devices mustobtain a maximum torsional rigidity while retaining a satisfactorylongitudinal flexibility and stiffness without kinking. They must alsomaintain a small outside diameter while providing a lumen as large aspossible.

SUMMARY OF INVENTION

The present invention relates to a novel apertured flexible tubularmember with an encasing for insertion into vessels of the body as partof a medical device. For example, the invention can be used ascatheters, including guide catheters and balloon catheters, guidewires,catheter sheaths for use with catheter introducers, or drug infusioncatheter/guidewires.

The preferred embodiment of the present invention will be coated with alow friction material such as a low friction polymer so as to providefor lubricity. Samples of materials that might be used are polyurethane,hydrogels, polyethylene, polytetrafluoroethylene (PTFE) and, inparticular, one such material which might be used is TEFLON®.

In some embodiments, such as catheters or sheaths, the inside of theflexible tubular member is also preferably coated with a low frictionmaterial such as hydrogel and/or with an anticoagulant such as heparin.The coating process might be accomplished by any number of well knownprocesses.

In yet another embodiment of the invention, slots of a predeterminedconfiguration are cut into a single, hollow, thin walled metal tube atpredetermined spacings, depth and pattern so as to provide the tube witha desired flexibility. The tube is then encased in a suitable lowfriction material as noted above or some other suitable coatingmaterial.

The use of the flexible tubular member within a fluid-tight encasingprovides flexibility to catheters, guidewires, catheter sheaths and druginfusion catheter/guidewires without subjecting them to the possibilityof kinking. In addition, because a metal tube is used, these devicesalso have high hoop strength, therefore, they are resistant to theforming of burrs or notches. Catheter sheaths made from the presentinvention can also be adapted for use with any conventional catheterintroducer parts to create an improved catheter introducer device.

The present invention is further explained hereafter with moreparticularity and reference to the preferred embodiment shown in thefollowing drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings wherein like reference numerals indicate correspondingparts throughout the several views:

FIG. 1 is a partial view of an embodiment of a catheter, guidewire,catheter sheath or drug infusion catheter/guidewire in accordance withthe principles of the invention wherein individual wound filamentscomprise substantially round wire;

FIG. 2 is a sectional view of the embodiment shown in FIG. 1;

FIG. 3 is a partial view of an alternative embodiment of the presentinvention wherein the filaments comprise substantially flat ribbon;

FIG. 4 is an elevational schematic illustration showing a multiplefilament jig winding filaments onto a mandrel in accordance with theprinciples of the present invention;

FIG. 5 is an elevational view of an embodiment of a multifilament jigwhich might be used in accordance with the principles of the presentinvention;

FIG. 6 is a partial side elevational view of an alternate embodiment ofa catheter, guidewire, catheter sheath or drug infusioncatheter/guidewire in accordance with the principles of the presentinvention wherein slots are cut into a wall of a thin walled tube;

FIG. 7 is a view similar to FIG. 6 illustrating the slots being spacedfurther apart;

FIG. 8 is a view similar to FIG. 7 illustrating the slots being spacedcloser together and continuous;

FIG. 9 is a partial side elevational view of a catheter, guidewire,catheter sheath or drug infusion catheter/guidewire in accordance withthe principles of the present invention wherein longitudinally extendingslots have been cut into the catheter, guidewire, catheter sheath ordrug infusion catheter/guidewire;

FIG. 10 is a view similar to FIG. 9 illustrating an alternate embodimentof a catheter, guidewire, catheter sheath or drug infusioncatheter/guidewire wherein a helical slot has been cut in the wall ofthe catheter, guidewire, catheter sheath or drug infusioncatheter/guidewire;

FIG. 11 is a sectional view of a balloon catheter comprising a cathetermade from the embodiment shown in FIG. 1;

FIG. 12 is an elevational view with portions broken away of a catheterintroducer, a guidewire and dilator after they have been advanced intothe blood vessel of a patient;

FIG. 13 is an elevational view of the catheter introducer having a fluidintroduction tube and having a dilator and guidewire inserted therein;

FIG. 14 is an elevational view of a prior art version of a catheterintroducer with portions broken away after it has been advanced into ablood vessel of a patient and the dilator unit and guidewire have beenwithdrawn, showing a kinked catheter sheath;

FIG. 15 is an elevational view of a representative guidewire type druginfusion catheter/guidewire with portions broken away after it has beenadvanced into a blood vessel of a patient and the core has beenwithdrawn;

FIG. 16 is an elevational view of a representative combination cathetertype and end hole guidewire type drug infusion catheter/guidewire devicewith portions broken away after it has been advanced into a blood vesselof a patient and the core wire has been withdrawn;

FIG. 17 is a partial perspective view of an alternate embodiment of acatheter, guidewire, catheter sheath or drug infusion catheter/guidewiremade in accordance with the principals of the present invention whereinslots are cut into a wall of a thin-walled tube by electrodes from anelectrostatic discharge machining tool;

FIG. 18 is a side elevational view of a first electrode for cuttingslots in a thin-walled tube as shown in FIG. 17;

FIG. 19 is a side elevational view of a second electrode for cuttingslots in a thin-walled tube as shown in FIG. 17;

FIG. 20 is a partial cross sectional view of a representative guidewireof the present invention;

FIGS. 21a and 21b are side views of a manufacturing method for creatingslots in a thin-walled tube as shown in FIG. 17;

FIG. 22 is a side view of an alternate manufacturing method for creatingslots in a thin-walled tube as shown in FIG. 17;

FIGS. 23a and 23b are perspective views of thin-walled tubes preparedfor exposure to light prior to being developed;

FIG. 24 is a side view of a method for screen printing a mask onto aphotoresist coated thin-walled tube;

FIG. 25 is a side view of a method for printing a photoresistivematerial layer onto a thin-walled tube; and

FIG. 26 is a sectional view of a guidewire made with a segment oftubing, made in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, FIGS. 1-3 illustrate two embodiments of acoated flexible tubular member in accordance with the principles of thepresent invention, generally referred to by the reference numeral 20,for use as a catheter, guidewire, catheter sheath or drug infusioncatheter/guidewire. As illustrated in FIGS. 1 and 2, the flexibletubular member 20 has a single layer multiwire coil 21 including sixwire filaments 22 which in this case comprise substantially round wire.It will be appreciated that differing numbers of filaments might beused; e.g. two to sixteen or more. In one embodiment, the filaments 22are made of spring tempered, stainless steel. In another embodiment, thefilaments are made of nitinol or ELGILOY®, which is acobalt-nickel-chromium alloy. The diameter of the wire, in theembodiment shown, is preferably 0.002 inches to 0.010 inches. It willalso be appreciated that a single filament coil or multi-layer coilcould be used with the invention.

As illustrated, both of the embodiments shown in FIGS. 1-3 arepreferably encased in a low friction material such as a low frictionpolymer or hydrogel for lubricity and to decrease thrombogenicity.Examples of materials which might be used are polyurethane,polyethylene, PTFE or TEFLON®. The thickness of this coating istypically 0.010 inches or less. Preferably the thickness of the coatingwill be less than the thickness of the filaments. The coating could beapplied in one of any well-known methods, such as dip coating, heatshrinking, spray depositing or vapor depositing the material to the coil21.

Illustrated in FIG. 3 is a helically wound single layer multiwire coil21 wherein the filaments 22 are made of flat ribbon 24. It will beappreciated that by varying the configuration of the multi-wire coil, acoated flexible tubular member 20 of varying characteristics can beformed. For example, making the individual coils more circular willresult in a flexible tubular member 20 which has a greater hoop strengthand stiffness, while making the individual coils more longitudinallyextending will result in less hoop strength but more flexibility. Havingfewer filaments, will result in increased flexibility but less hoopstrength. Increasing the size of the filaments will result in increasedhoop strength but less flexibility.

Moreover, varying the configuration of the multi-wire coil along thelength of the flexible tubular member 20 can result in a flexibletubular member 20 with varying characteristics. For example, the middlesection of the flexible tubular member 20 could be made more flexible byreducing the diameter, reducing the number of filaments, increasing thespacing between filament coils, etc., while the distal end of a flexibletubular member 20 could be arranged to have a higher hoop strength toprevent burring or notching. A flexible tubular member 20 could also bemade where the distal end is very flexible and the proximal end is verystiff to improve the transmission of a torque at the proximal end to thedistal end. Moreover, a flexible tubular member 20 can be made whichvaries in stiffness continuously throughout its length. A flexibletubular member 20 can also be made wherein the variation in flexibilityor stiffness from one location to the next is very gradual andcontinuous.

In addition, the flexibility of the flexible tubular member 20 couldalso be reduced by selectively welding adjacent windings of the coil 21.By welding adjacent windings, the relative movement between the windingsis eliminated and the flexibility of the coil in the area adjacent tothe weld would be reduced. Therefore, a flexible tubular member 20having variable flexibility along its length could be made from a coil21 with a single winding configuration that had selective windingswelded together.

Illustrated in FIGS. 4 and 5 is one method for making the flexibletubular member 20 embodiment shown in FIGS. 1-3. As shown in FIG. 4, ajig 30 has a portion 32 with apertures 34 disposed therein generallyabout its periphery. The filaments 22 are slidably disposed in theapertures 34 and are fed from supply reels or the like (not shown). Thecenter of the jig 30 has an aperture 36 for insertion therethrough of amandrel 38. The mandrel 38 would typically have a diameter of one inchor less. The ends of the filaments 22 are suitably attached to themandrel 38 at the beginning of the winding process. It will beappreciated that the jig 30 might take on any number of suitableconfigurations. For example, as opposed to apertures, guide arms mightbe used to guide the filaments. Moreover, the jig might be replaced witha plurality of arms which are movable radially toward and away from themandrel.

As illustrated in FIG. 4, the mandrel 38 is inserted through theaperture 36 in the jig 30 and the mandrel 38 is rotated as the mandrel38 is moved in a downstream direction as generally indicated by thearrow 40. As a result, the filaments 22 are wound onto the mandrel so asto form the single layer multiwire coil 21. The filaments 22 aremaintained under very high tension as they are wound onto the mandrel.The tension of course will vary depending on a number of factors.Varying the rate of rotation and the rate of longitudinal movement willresult in varying configurations of coils.

The coil 21 is then encased in a suitable low friction material as notedabove so as to form a coated flexible tubular member 20 for use as acatheter, guidewire, catheter sheath or drug infusioncatheter/guidewire. In one embodiment, the mandrel is movedlongitudinally and is rotated, although the jig could just as well bemoved and rotated. A typical speed of movement might be one inch perminute, while a typical rate of rotation might be ten revolutions perminute (RPM).

A programmable controller might be used to control the operation of thejig 30 and the mandrel 38 so as to enable precise control of the windingprocess such that very specific coil configurations can be achieved aswell as variations thereof. Those skilled in the art would recognizethat several other well known coil winding methods could be used withthe invention.

Illustrated in FIGS. 6-10 are alternative embodiments of the flexibletubular member 20 for use as a catheter, guidewire, catheter sheath ordrug infusion catheter/guidewire. These embodiments comprise a singlemetal tube 50, with a wall thickness of roughly 0.001 inches to 0.010inches. The tube 50 has a plurality of slots 52 disposed therein to forma flexible tubular member 20. The preferred tube material would bestainless steel or nitinol, however, the tube material could be springtemper steel such as the product brand ELGILOY®, or another suitablealloy material. The tube 50 is encased in a suitable low frictionmaterial as noted above for the embodiments shown in FIGS. 1-3 so as toseal off the slots making it fluid tight. The inner surface of the tube50 is preferably coated with a similar low friction material such asTEFLON®, PTFE or FEP so as to provide low friction. Typically thethickness of the outer and inner coating will be 0.001 inches to 0.003inches or less. It will be appreciated that by varying the configurationof the slots, their depth, and the spacing between the slots, theflexibility, longitudinal stiffness and hoop strength of the flexibletubular member 20 can be varied. In addition, the variation of thecomposition and thickness of the coating material will also vary theflexibility of the coated flexible tubular member 20 for use as acatheter, guidewire, catheter sheath or drug infusioncatheter/guidewire. Moreover, the metal tube 50 might be bent and heattreated to pre-form curves and configurations as desired.

In one embodiment, the slots are cut totally through the tubing wall 50by use of a an electrostatic discharge machining tool (EDM). To cut theslots using the EDM machine, both ends of the tube 50 are fastened to aholding device such that the tube 50 is positioned between two or moreEDM wires. The holding device would then position the tube 50 at thedesired location for cutting a slot. The EDM wires would then be movedinward to cut the desired slot. The EDM wires would then translateoutward beyond the outer diameter of the tube 50. The holding devicewould then rotate and/or translate the tube 50 to the desired positionfor cutting another set of slots. The EDM wires would then be movedinward to cut the next set of slots. This procedure would be repeatedthroughout the tube 50 to create a flexible tubular member 20. Thoseskilled in the art would recognize that multiple holding devices andmultiple EDM wires could be used to simultaneously cut multiple slotsinto multiple tubes 50 to simultaneously create multiple flexibletubular members 20.

In the preferred embodiment, the slots are cut totally through thetubing wall 50 by use of a plunge EDM machine. As recognized by thoseskilled in the art, a plunge EDM machine utilizes charged electrodesthat are arranged and configured to cut a predetermined shape when theyare plunged into a base material. As shown in FIG. 17, a plunge EDMmachine with first and second electrodes 80, 81 can be utilized to cutan alternating pattern of slots 52 in the thin-walled tube 50 that areoffset by 90°.

As shown in FIG. 18, the first electrode 80 would be generallyrectangular in shape with a notch 82 that is triangular in shape with arectangular extension 83. The depth of the notch 82 would be greaterthan the radius of tube 50 such that a portion of the tube 50 would bedisplaced within the rectangular extension 83 of the notch 82 when thefirst electrode 80 is plunged into the tube 50. Because a portion of thetube 50 is displaced within the rectangular extension 83, that portionis not in contact with the first electrode 80 and is not cut. Oneexample of a first electrode 80 for cutting slots 52 as shown in FIG. 17would have an angle θ₁ of 82° and a rectangular extension 83 with awidth of 0.010 inches.

As shown in FIG. 19, a second electrode 81 would be generallyrectangular in shape with a triangular notch 84. The triangular notch 84would have a depth that is less than the radius of the tube 50 and anangle θ₂ that is more than 90°, preferably 94°. Because the depth of thetriangular notch 84 is less than the radius of the tube 50, a portion ofthe tube 50 will extend beyond the second electrode 81 as shown in FIG.17 and will not be cut.

In the preferred embodiment, a second pair of first and secondelectrodes (not shown) would be oppositely disposed from the first andsecond electrodes 80, 81 shown in FIG. 17. First, the tube 50 would besecured on both ends. Then, the first pair of electrodes would beplunged into the tube 50 to cut half of a pair of slots 52 as shown inFIG. 17. Then, the first pair of electrodes would be removed and thesecond pair of electrodes would be plunged into the tube 50 to completethe creation of the pair of slots 52 as shown in FIG. 17. Those skilledin the art would recognize that multiple pairs of electrodes 80, 81could be displaced along the length of the tube 50 to cut apredetermined pattern of multiple slots 52 in the tube 50 without havingto translate either the tube 50 or the electrodes 80, 81. Those skilledin the art would also recognize that other electrode configurationscould be used to cut other patterns of slots in the tube 50. Moreover,those skilled in the art would recognize that a laser or other suitableslot cutting tools such as wet chemical and acid etching tools could beused with the present invention.

In other embodiments, the slots or apertures may be cut completely orpartially through the tubing wall 50 of a tubular element by wetchemical and acid etching techniques or "chemical milling" to producestructures including slotted hypotubes. Such slots or apertures couldalso be referred to as "slits", "notches" or "etches." The slots orapertures could also have a variety of shapes which may be suitable suchas round, square or rectangular.

"Chemical milling" involves coating a stainless steel or nitinol tubewith a layer of a positive or negative photoresist material, exposingand developing selected portions of the photoresist material layer,cutting the slots in the tube with chemicals in a chemical etchingsolution, and removing the remaining photoresist material (and othercoating materials if present). Alternate chemical milling methodsinvolve coating a stainless steel or nitinol tube with a layer ofchemically resistant material, cutting the slots in the tube withchemicals in a chemical etching solution, and removing the remainingchemically resistant material (and other coating materials if present).

As shown in FIGS. 21a and 21b, there is a first manufacturing processfor preparing a tube 120, prior to the photoresist layer being developedand slots chemically milled into the tube. The tube 120, preferably athin-walled tube, coated with a layer of photoresistive material 122 ispositioned on a mandrel 124, or other rotatable tube holding structure.This tube 120 is arranged in close proximity to pattern masks (e.g.,photographic film tools) 126 (FIG. 21a), 127 (FIG. 21b), in conjunctionwith a light source 128 that is controlled by passing through anaperture 130. The light source 128 provides light (indicated by arrows131), at a wavelength sufficient to expose the photoresistive layer 122at selected locations.

The photoresistive layer 122 typically includes positive or negativephotoresistive polymers commonly known in the art. Some positivephotoresistive polymers that may be used are Novolak® based materialssuch as Photoposit® 111 Photo Resist, Photoposit® 119 S Photo Resist andPhotoposit® SP 20-29 Photo Resist, all available from Shipley Company,Inc., 500 Nickerson Road, Marlborough, Mass. 01752. Some negativephotoresistive polymers that may be used are KTFR Negative Photoresist,from KTI Chemicals Incorporated, 2 Barnes Industrial Park Road,Wallingford, Conn. 06492. These positive or negative photoresistivepolymers are applied to the tube 120 by techniques such as spraying,vapor deposition, or dip coating, as well as other conventional coatingtechniques known it the art.

The light from the light source 128 is preferably columnated and of awavelength between approximately 350-400 nm, but may be varied dependingon the particular photoresistive material employed. The light may becontrolled by a shutter, subject to manual or automated (computer)control.

The photoresist coated tube 120 is patterned or "printed" as the tube120 is rotated on the mandrel 124 (in the direction of arrow 132).Simultaneously (as shown specifically in FIG. 21a), the pattern mask 126having apertures (not shown) is translated across the photoresist coatedtube 120 in an arcuate path (in the direction of arrow 134). The arcuatepath allows the flat pattern mask 126, corresponding to the slots 52 orapertures on the finished tube 50 (FIG. 17), to be applied to therounded surface for creating a pattern on the tube 120.

Alternately (as shown specifically in FIG. 21b), the photoresist coatedtube 120 could be rotated as the mandrel 124 rotates (in the directionof arrow 142), as the flat pattern mask 127 having apertures 144, ismoved laterally (in the direction of arrow 146). The rotating of themandrel 124 and the photoresist coated tube 120, coupled with movementof the screen 144 is coordinated such that a portion of the photoresistlayer is exposed for creating a pattern on the tube 120, thatcorresponds to the slots or the apertures of the finished tube 50 (FIG.17). This procedure is repeated throughout the length of the tube 120,to create a pattern for the slots over the entire length of the tube120.

FIG. 22 shows a second manufacturing process for preparing a tube,preferably a thin-walled tube, prior to the photoresist layer beingdeveloped and slots chemically milled into the tube. The tube 150,coated with a layer of photoresistive material 152, as described above,is positioned on a mandrel 154, or other rotatable tube holdingstructure. A mask (phototool) 156, preferably in the form of a glasstube having a pattern written (printed) onto its inner or outer surface,is then placed concentrically over the tube 150. This mask 156 has aninner diameter slightly larger than the outer diameter of the tube 150so the photoresist coated tube 150 can fit snugly within the mask 156.This tube 150 is arranged in close proximity to a light source 158 thatis controlled by passing through an aperture 160. The light source 128provides light (indicated by arrows 161), preferably columnated, at awavelength sufficient to expose the photoresistive layer 152 at selectedlocations (corresponding to the slots or apertures of the finishedtube), as the tube 150 is rotated exactly together with the mask 156 (inthe direction of arrow 164).

FIGS. 23a and 23b show a third manufacturing process for preparing thepreferably thin-walled tubes, prior to the photoresist layer beingdeveloped and slots chemically milled into the tube. The tubes 170, 171are initially coated with a layer of photoresistive material 172, asdescribed above. Pattern masks (phototools), in the form of films 178,179 with apertures 180, 181 (corresponding to the slots or apertures tobe cut into the finished tubes), are wrapped around the photoresistcoated tube 170. The films 178, 179 could be a sheet 178 or series ofsheets attached to the photoresist coated tube 171 (FIG. 23a) or a strip179 wrapped around the photoresist coated tube 170 (FIG. 23b). Once thefilms 178, 179 are secured to the respective photoresist coated tubes170, the photoresist coated tubes 170, 171 would be positioned on themandrel 154 (FIG. 22) or other similar rotatable tube-holding structure,and processed in accordance with the above disclosed secondmanufacturing process that is detailed in FIG. 22.

FIG. 24 details a fourth manufacturing process for preparing the tubeprior to the photoresist layer being developed and slots chemicallymilled in to the tube. The tube 190 is initially coated with a layer ofphotoresistive material 192, as described above. This photoresist coatedtube 190 is then placed between an upper screen 194 (moveable laterallyin the direction of arrow 195) and lower support rollers 196. An roller198 (rotating in the direction of arrow 200), coated withchemically-resistant ink, preferably acid resistant ink, is positionedabove the screen 194.

The movement of the screen 194 is coordinated with the rotation of theink coated roller 198 such that ink is forced through apertures (notshown) in the screen 198, rotating the tube 190 (in the direction ofarrow 201), resulting in the entire photoresist coated surface 192 ofthe tube 190 being correctly patterned. The pattern corresponds to theslots or apertures of the finished tube, as the inked portions of thephotoresist coated tube serve as the mask. The photoresist coated tube190 can then be placed on a mandrel 154 (FIG. 22) or other similar tubeholding structure and processed in accordance with the secondmanufacturing process disclosed above and detailed in FIG. 22.Alternately, this inked pattern could be applied by laser printing orink jet printing (described below).

There is a fifth manufacturing process (not illustrated) for preparingthe tube prior to the photoresist layer being developed and slotschemically milled into the tube. The tube is coated with a layer ofphotoresistive material, as described above. This photoresist coatedtube is then placed inside of a stationary glass tube that serves as amask (phototool), as this stationary tube includes a pattern of pin-holeapertures. This stationary glass tube mask is arranged in closeproximity to a light source. As the photoresist coated tube is rotated,the light source is activated at predetermined times, corresponding topredetermined rotational locations of the photoresist coated tube. Thisaction exposes the photoresist coated tube at locations corresponding tothe slots or apertures of the finished tube.

Once the photoresist coated tubes are prepared by any of the abovemethods, these tubes, coupled with their respective masks, could also beexposed by being subjected to laser radiation as a substitute for theabove disclosed light sources. For example, the laser radiation could befrom an excimer laser or ultraviolet (UV) laser, to expose predeterminedlocations on the tube. The exposed locations would correspond to theslots or apertures of the finished tube. Moreover, laser radiation maybe applied directly to non-masked photoresist coated tubes, exposing thetubes at predetermined locations, corresponding to the slots orapertures of the finished tube.

The exposed tubes are then developed as either a positive or a negative,with suitable developers depending on the photoresistive materialemployed. For example, if positive photoresistive materials, such asPhotoposit® 111, 119 S, or SP 20-29 (all disclosed above) are employed,Photoposit® 303 A Developer, available from Shipley Company, Inc., 500Nickerson Road, Marlborough, Mass. 01752 may be the developer. Forexample, if the negative photoresistive material KTFR NegativePhotoresist (disclosed above) is employed, KTFR Developer, availablefrom KTI Chemicals Incorporated, 2 Barnes Industrial Park Road,Wallingford, Conn. 06492 may be used. The developed tube may now bechemically milled, preferably by placement in an acid bath for chemicaletching.

The chemical etchant is preferably an acid etchant, such as ferricchloride of a photoengraver's grade at 36-42 degrees Baume in a bath atapproximately 125 degrees F. Other etchants include solutions of ferricchloride and hydrochloric acid, a five volume solution of one volumeconcentrated hydrochloric acid (37%), one volume concentrated nitricacid (70%), and three volumes of water, this etchant under similarconditions as above, and Ferric Chloride at approximately 42 degreesBaume at approximately 130 degrees F. (hydrochloric acid may be added).The tube is removed from the bath after approximately thirty seconds toten minutes and the time depends on the depth and width of the slotsdesired, as well as the thickness of the metal substrate (i.e., thetubular element). (Under these conditions, stainless steel etches atapproximately 0.5 mm/minute). Alternately, the tube can be removed fromthe bath, proximal end first, followed by its distal end. This allowsthe acid additional time to etch at the distal end, such that the slotscut at this end will be wider, giving the distal end greater flexibilitythan the proximal end.

Greater flexibility at the distal end of the tube (as opposed to theproximal end) can also be achieved by employing the above disclosedmasks having patterns with the portions that correspond to the locationsof the chemically milled slots (of the finished tubes) being closer toeach other at the distal end. Upon conclusion of a chemical etch(disclosed above), the slots at the distal end are closer to each otherthan the slots at the proximal end.

The photoresistive material (as well as other materials such as inks)that remains on the tube is then removed by techniques such as strippingwith chemicals compatible with the positive or negative photoresistivematerials remaining on the tube. For example, if positive photoresistivematerials, such as Photoposit® 111, 119 S, or SP 20-29 (all disclosedabove) are employed, Photoposit® Remover 1112A, available from ShipleyCompany, Inc., 500 Nickerson Road, Marlborough, Mass. 01752 may be usedto strip the remaining photoresist (as well as other material remainingon the tube). For example, if the negative photoresistive material KTFRNegative Photoresist (disclosed above) is employed, Products 13/LS,14/HS, 14/KS and ICL/8000, all available from Photofabrication Chemicaland Equipment Company, 522 Route 30, Frazier, Pa. 19355 may be used tostrip the remaining photoresist from the tube. Other strippers may beadded to stripping mixture to remove other materials, such as inks, thatmay also be remaining on the tube. These other strippers may becompositions such as, Products 68, SS1, THP, GPS and PRS-3, allavailable from Photofabrication Chemical and Equipment Company, 522Route 30, Frazier, Pa. 19355. Alternately, other photoresist strippingtechniques, well known to those skilled in the art, could also be usedto remove the photoresist and any other material remaining on the tube.

In an alternate embodiment of chemical milling, the chemically resistantmaterial, such as the photoresistive materials disclosed above, as wellas other acid resistant materials, could be coated onto the stainlesssteel or nitinol tube in a pattern conforming to the slots or aperturesto be cut, by methods such as ink jet printing or screen printing.

FIG. 25 details an automated, computer controlled, ink jet printingmethod for applying chemically resistant material to a tube 210 in apredetermined (preprogrammed) pattern, corresponding to the slots orapertures to be cut partially therein or completely therethrough. Thetube 210 is held on a print lathe 212 by collects 214. Motors 216 on thelathe 212 drive the collects 214, such that the tube 210 is rotated. Thelathe 212 also includes a print head 218, through which the chemicallyresistant material, from a supply 220, is printed onto the tube 210. Aguide 222 on the print head 218 (FIG. 25) as well as secondary guide(s)224 (only one shown) on the lathe 212 maintain the tube 210 in theproper position. The guide 222 on the print head 218 is attached theretoby bolts 226. Screws 228, preferably made of plastic, extend laterallythrough the guide 222, and serve to retain the tube 210 in the properposition during printing.

The lathe 212 is mounted on wheels 230, the wheels being received onlands 231. The lathe 212 is also attached to a belt 232 or otherequivalent carriage. The belt 232 is driven by a motor 234. All of themotors 216, 234 and the head control 236 for the print head 218 arepreferably controlled by a computer 238 or other similar microprocessor.The belt 232 moves to translate the tube 210 as the chemically resistantmaterial is patterned onto the rotating tube 210. The preferredtranslation distance is approximately one meter in both directions(represented by arrows 239a, 239b) so that the entire tube can beprinted. Printing can be in one or both directions, depending upon thelength of the tube.

This method could also be used to place an inked pattern, correspondingto slots or apertures of the finished tube, onto a photoresist coatedtube (the photoresist coated onto the tube by spraying, vapordeposition, dip coating etc., as disclosed above). The ink would beapplied as a light (radiation) blocking layer onto the photoresistivematerial coating from the print head 218 of the lathe 212, in accordancewith a computer controlled pattern. The photoresist coated tube wouldthen be exposed by the light sources or laser radiation, as disclosedabove. The exposed tubes would be developed, in accordance with theprocedures disclosed above, and chemically milled in accordance with thechemical etching methods disclosed above.

This method could also be used with a tube to make a tubular mask(phototool), such as the mask 156 in FIG. 22. In this case, the tubewould be processed similar to that described above, except maskingmaterial (i.e., ink) would be placed into the supply 220, such that theprint head 218 would print this masking material onto the tube.

Slots are then cut into the tube by chemical milling, as the coatedpatterned tube is chemically etched by placement into the bath of acidetchant described above, in accordance with the methods described above.Once the chemical etch is complete, the chemically resistant material(and any other materials, e.g., ink) remaining on the tube is removed bythe stripping processes described above. The tube may then be encased ina suitable low friction material, as described above, to seal off theslots (if cut completely through the tube) making the tube fluid tight.

In another embodiment, that may be used to produce slotted hypotube,slots or apertures are cut into a tubular element (tube) by a processreferred to as laser ablation. In this process, the tube is coated witha chemically resistant material, such as Teflon® or polyimide. A patternof apertures would then be made in the coated tube as radiation (light)from a laser would ablate or burn off portions of the chemicallyresistant material coating, corresponding to the slots or apertures ofthe finished tube. The tube would then be chemically milled bychemically etching the tube in an acid etchant bath, as described above,in accordance with the methods described above. Slots at the distal endof the tube could be cut wider and/or closer together than those at theproximal end of the tube, to provide the tube with greater flexibilityat the distal end. The remaining coating material would then be strippedby conventional techniques. Additionally, a laser may be used to cut theslots or apertures directly into the tubular element, either partiallyor completely therethrough, in various shapes and sizes.

In some embodiments, the slots 52 or apertures need not be cutcompletely through the tubing wall 50. Such apertures could also bereferred to as "slits", "notches" or "etches." The apertures could alsohave a variety of shapes which may be suitable such as round, square orrectangular apertures. It will be appreciated that the flexible tubularmember 20 might be manufactured in any number of ways in keeping withthe principles of the invention. For example, holes of a suitablepattern might be cut in a flat sheet of material such as stainless steelor nitinol which is then rolled and welded into the appropriate shape.In yet other methods, holes of a suitable pattern might be cut in athicker, shorter tube of metal which is then drawn into an appropriateshape.

In FIGS. 6-8 the slots are shown as running generally transverse to thelongitudinal axis of the flexible tubular member 20. The flexibletubular member 20 shown in FIG. 6 is more flexible than the flexibletubular member 20 shown as FIG. 7 as the slots 52 are closer together.One example of the spacing between slots is 0.05 to 0.10 inches. Theflexible tubular member 20 of FIG. 8 has a continuous slot (of pluralapertures) in a spiral and is very flexible.

In FIG. 9, an alternate embodiment is shown wherein the slots 52 extendlongitudinally of the tube 50. In FIG. 10, a slot 52 is shown asextending helically about the tube 50. It will be appreciated that anynumber of different slot configurations might be created in the tube 50.Moreover, the configuration of the slots might be varied along thelength of the tube 50 so as to provide a flexible tubular member 20 withvarying characteristics along its length.

A further explanation of the invention for use as a catheter, includinga guide catheter or balloon catheter, a guidewire, a catheter sheath ordrug infusion catheter/guidewire is provided hereinafter.

Catheters

As described earlier, the various embodiments of the invention can beused as catheters. The inside and outside diameters of the catheters mayvary, however, some catheters have an outside diameter from 0.010 inchesto 0.250 inches or larger. The use of the invention as a catheter isparticularly advantageous because one can make a catheter having variedcharacteristics along its length. For example, the distal end of thecatheter typically must be very flexible, while other areas of thecatheter must be stiffer to provide the longitudinal stiffness totransmit the torque required to maneuver the catheter. Theserequirements can be met by varying the windings of the coils 21 or bywelding adjacent windings of the coil 21 as described in the firstembodiment of the invention or by varying the configuration of the slots52 in the flexible tubular member 20 as described in the secondembodiment of the invention.

FIG. 11 illustrates a balloon type catheter 60 utilizing an embodimentof the flexible tubular member 20 for use as a catheter shown in FIG. 1.The balloon catheter 60 includes an expandable balloon portion 62interconnected to lumen 64 of the catheter 20 by ports 66. The balloonportion is expanded to temporarily obstruct the passageway of a coronaryartery or the like during angioplasty treatment.

Guidewires

As described earlier, a coated flexible tubular member 20 in accordancewith the invention can be used as a guidewire. The guidewires that arecurrently used are comprised of a core wire that is welded to the innersurface of a spring coil. TEFLON® is then spray coated on the outside ofthe device to complete the assembly of the guidewire. However, in orderto make these guidewires steerable, the core wire has a series ofelaborate tapering schemes to vary the stiffness and flexibility of thevarious portions of the guidewire.

As shown in FIG. 20, a guidewire 100 made according to the presentinvention would be comprised of a core wire 101 that is attached to aflexible tubular portion 20 made according to any of the previouslydescribed embodiments of the invention. In FIG. 20, the followingconfiguration is shown by way of example: a core wire 101 attached tothe distal end of the guidewire 100 and having a single tapered section;a slotted tubular portion 102; and a coli 103 attached between the corewire 102 and the distal end. The outer surface of the tubular portion 20is covered with an appropriate biocompatable encasing 104 as describedhereinabove. However, various other guidewire configurations could beemployed within the scope of the present in invention. For instance, thecore wire 101, could have multiple tapered sections or it could be ofconstant or other variable cross section; it also does not have to beattached at the distal end of the guidewire 100. Other variations knownin the prior art could include the addition of a safety ribbon, theelimination of coil 103 (so that the tube extends to the distal end), orthe addition of more coiled sections. The length of these guidewireswould typically range from 150 centimeters to 300 centimeters and theflexible tubular member 20 would have an outside diameter between 0.010and 0.065 inches.

By varying the flexibility of the flexible tubular member 20 along thelength of the guidewire as described above, a guidewire in accordancewith the present invention can achieve the functions of currentguidewires without the need for elaborate tapering schemes for the corewire. For example, as described in the first embodiment, the distal endof the guidewire could be made very flexible by using a coil 21 withmore longitudinally displaced windings, while the proximal end of theguide wire could be made stiffer by having more circular windings or bywelding adjacent windings together. As previously described in thesecond embodiment, as well as those embodiments produced byElectrostatic discharge machining (EDM) and chemical milling, the sameresult could be achieved by varying the configuration of the slots 52 inthe tube 50.

FIG. 26 shows a guidewire 250 made with slotted hypotube prepared inaccordance with the present invention. This guidewire 250 is formed of acore wire 252 having a tapered distal portion 254. A tubular member 256,preferably made of a slotted hypotube segment in accordance with theinvention, is then welded onto the tapered distal portion 254 of thecore wire 252 at weld or solder joints 258. A blunt nose piece 260 isformed, preferably by burnishing, at the distal end 262, as the corewire 252 and the tubular member 256 are welded or soldered together.Specifically, the slots 264 at the end of the tubular member 256 at thefar distal end 266 of the guidewire 250 are preferably wider than theother slots 264 of the tubular member 256. This configuration providesthe guidewire 250 with greater flexibility at the distal end 262.

Catheter Sheaths and Catheter Introducers

As described earlier, a coated flexible tubular member 20 in accordancewith the invention could also be used as a catheter sheath. The insideand outside diameter of catheter sheaths may vary to meet differentintroducer and catheter requirements; however, several embodiments of acatheter sheath have an outside diameter from 0.050 inches to 0.300inches or larger. As described earlier, catheter sheaths require a highhoop strength at the distal end to prevent burring and notching andflexibility in the center portion to prevent kinking. To meet therequirements, the windings of the coil 21 in the first embodiment of theinvention can be varied or welded to provide a high hoop strength at thedistal end of the catheter sheath and the center portion of the cathetersheath can be made flexible to prevent kinking. Likewise, theconfiguration of the slots 52 in the tube 50 of the second embodimentcan be varied to produce the same characteristics.

As shown in FIGS. 12 and 13, a coated flexible tubular member 20according to the present invention for use as a catheter sheath can beincorporated into a catheter introducer, generally designated as 90. Inthe preferred embodiment, the introducer 90 would have a hub 94 withhemostasis valve means that is connected to the coated flexible tubularmember 20 (catheter sheath) and to a feed tube 91 having a three-waystop cock 92. Those skilled in the art will recognize that anyhemostasis valve means such as those disclosed in U.S. Pat. Nos.4,000,739 and 4,610,665 could be used with the present invention. Thefeed tube 91 is arranged and configured to allow the insertion of fluidsthrough the hub 94 and catheter sheath 20 and into the patient's bloodvessel.

The hub 94 and catheter sheath 20 are also arranged and configured toallow the insertion of a dilator 93 through the lumen of the hub 94 andcatheter sheath 20. The dilator 93 would contain a lumen that isarranged and configured to allow the insertion of a guidewire 95 throughthe dilator 93. In the preferred embodiment, the dilator 93 is generallycylindrical in shape with a tapered distal end and having a stop portion96 generally located at its proximal end that is arranged and configuredto temporarily secure the dilator 93 to the hub 94. The dilator 93 alsohas an outer diameter that is approximately equal to the diameter of thelumen in the catheter sheath 20 so as to provide an interference fit tosupport to the catheter sheath 20 during its insertion into the bloodvessel. Those skilled in the art would recognize that other dilators 93could be used with the invention.

Drug Infusion Catheter/Guidewires

As described earlier, drug infusion catheter/guidewires can also be madeaccording to the present invention. As shown in FIG. 15, a guidewiretype drug infusion catheter/guidewire 70 is located within the lumen ofa blood vessel 72 with occlusion 73. The guidewire type drug infusioncatheter/guidewire 70 would be comprised of a flexible tubular member 20made in accordance with the previously described invention having sideholes 71 near its distal end and a removable core wire (not shown). Likeguidewires, the flexible tubular member 20 would have a small outsidediameter ranging between 0.01 and 0.05 inches.

In use, the flexible tubular member and removable core would be advancedtogether through the patient's circulatory system like a conventionalguidewire until reaching the desired location. Therefore, the use of aflexible tubular member 20 in accordance with the various embodiments ofthe invention previously described in the discussion on guidewiresprovides the guidewire type drug infusion catheter/guidewire with therequired flexibility and torquability to maneuver the device through thecirculatory system. After reaching the desired location, the core isremoved leaving only the flexible tubular member 20 within the patient.Drugs or other fluids can then be pumped through the lumen of theflexible tubular member 20 and out the holes 71 and into the occludedportion of the blood vessel 72. As shown in FIG. 16, a second embodimentof a guidewire type drug infusion catheter/guidewire 70 could be madevery similar to the previously described device in FIG. 15 except thatthe second embodiment would contain a hole in the distal end 76 andwould not contain side holes 71 as shown in FIG. 15.

However, because the outside diameters of the flexible tubular member 20in the guidewire type drug infusion catheter/guidewire devices are sizedlike guidewires, the lumen size of the flexible tubular member islimited. Therefore, the flowrate of drugs through the lumen is limited.If a larger flowrate or if a similar flowrate must be supplied with alower source pressure, a catheter type drug infusion catheter/guidewire74 might be used. The catheter type drug infusion catheter/guidewire 74would be comprised of a flexible tubular member 20 made in accordancewith the previously described embodiments of the invention for use as acatheter, except that it would have a tapered distal end 77 and sideholes 75 near its distal end 77. The catheter type drug infusioncatheter/guidewire 74 would be advanced over a guidewire or a guidewiretype drug infusion catheter/guidewire 70, as shown in FIG. 16. Uponreaching the desired location, drugs or other fluids would be pumpedthrough the catheter type drug infusion catheter/guidewire 74 andthrough the side holes 75 into the blood vessel near the occludedlocation. Because the catheter type drug infusion devices 74 have alarger lumen than the guidewire type drug infusion devices 70, the drugsor other fluids can be delivered to the desired area at a lowerpressure.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present invention have been setforth above in the foregoing description, together with details of thestructure and function of the invention, the disclosure is illustrativeonly, and changes may be made in detail, especially in matters of shape,size and arrangement of parts within the principles of the invention tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

What is claimed is:
 1. A method for producing a flexible tubular devicecomprising:a. providing a tubular element including an outer surface,the tubular element being sized for intravascular insertion within ahuman body; b. providing a light source; and c. creating a desiredpattern on the tubular element by:1) applying a photoresistive materialto at least a portion of the outer surface of the tubular element; 2)providing a mask intermediate the tubular element and the light source,at least a portion of the mask including a mask pattern having locationstranslucent to light from the light source; 3) activating the lightsource to selectively expose the photoresistive material on the outersurface of the tubular element, such that exposed and unexposedlocations are created on the photoresistive material; 4) developing thephotoresistive material on the tubular element; and 5) removing segmentsof the tubular element corresponding to either the exposed or unexposedlocations of the photoresistive material such that the tubular elementis provided with the desired pattern, the desired pattern including aplurality of apertures that extend completely through the tubularelement between an inner and outer diameter of the tubular element, theplurality of apertures being arranged and configured for providing thetubular element with in a desired flexibility suitable for intravascularoperations.
 2. The method of claim 1, wherein some of the aperturesextend partially through the tubular element.
 3. The method of claim 1,wherein the apertures are rectangular.
 4. The method of claim 1, whereinthe apertures are round.
 5. The method of claim 1, wherein the tubularelement is metal.
 6. The method of claim 5, wherein the tubular elementis stainless steel or nitinol.
 7. The method of claim 1, wherein themask includes a patterned tube for concentric placement around thetubular element.
 8. The method of claim 1, wherein the mask includes apatterned film having a length approximately equal to the circumferenceof the tubular element.
 9. The method of claim 1, wherein the lightsource is a laser.
 10. The method of claim 1, wherein the flexibletubular device is a catheter.
 11. The method of claim 1, wherein theflexible tubular device is a catheter sheath.
 12. The method of claim 1,wherein the flexible tubular device is a drug infusion catheter.
 13. Themethod of claim 1 additionally comprising removing the remainingphotoresistive material.
 14. The method of claim 13 additionallycomprising laminating the tubular element with a coating.
 15. The methodof claim 14, wherein the laminated coating is a polymeric material. 16.The method of claim 1, wherein the step of developing the photoresistivematerial includes developing the photoresistive material positively ornegatively.
 17. The method of claim 1, wherein the step of removing thesegments of the tubular element includes chemical etching.
 18. A methodfor producing a flexible tubular medical device comprising:providing atubular element sized for intravascular insertion in a human body, thetubular element including an outer surface; providing a light source;applying a photoresist to at least a portion of the outer surface of thetubular element; providing a pattern mask intermediate the tubularelement and the light source; exposing the photoresist by directinglight from the light source through the mask; rotating the tubularelement about its longitudinal axis; translating the mask across thetubular element; coordinating the operation of the light source with themovement of the tubular element and the mask such that an exposedpattern and an unexposed pattern are generated on the outer surface ofthe tubular element; developing the photoresist to remove first regionsof the photoresist that correspond to one of the exposed and unexposedpatterns; and removing first portions of the tubular element thatcorrespond to the first regions of the photoresist such that the tubularelement is provided with a desired pattern, the desired patternincluding a plurality of apertures that extend completely through thetubular element between an inner and outer diameter of the tubularelement, the plurality of apertures being arranged and configured forproviding the tubular element with a desired flexibility suitable forintravascular operations.
 19. The method of claim 18, wherein thepattern mask is substantially flat.
 20. The method of claim 19, whereinthe pattern mask is translated substantially along a planar path. 21.The method of claim 19, wherein the pattern mask has a patterned regionhaving a length at least substantially equal to an outer circumferenceof the tubular element.
 22. The method of claim 19, wherein the patternmask comprises a patterned film.
 23. The method of claim 18, wherein thepattern mask is substantially curved.
 24. The method of claim 23,wherein the pattern mask is translated substantially along a curvedpath.
 25. The method of claim 23, wherein the pattern mask has apatterned region having a length at least substantially equal to anouter circumference of the tubular element.
 26. The method of claim 3,wherein the pattern mask comprises a patterned film.